This invention relates to microscope slides which include electrodes for the examination of organic cells, particularly such slides which are adapted for the study of the electrophysiological behavior of neurons or nerve cells and their processes.
In order to examine the electrophysiological activity of living nerve cells, it is necessary to apply electrical potentials, currents, impulses, etc. to individual cells or to certain parts of a cell, such as the cell processes (neurites), by means of suitable electrodes located in microscopically close proximity to each other. Such electrodes must have contact surfaces of microscopic size, e.g., 1-10 microns, and must present a sufficiently small electrical contact impedance to the cell, as well as exhibiting other characteristics suitable for allowing such electrodes to contact the desired cells or cell areas without harming the cell matter. There have hitherto not been any satisfactory solutions for these requirements, especially where several simultaneous connections on different parts of a small volume of tissue are desired.
It is known, for example, to utilize an electrode consisting of a very thin wire of a hard material, such as tungsten, which is set in a small glass tube. The free end of the wire, which protrudes slightly from the end of the glass tube, is brought into contact with particular areas of the cell by manipulation of the electrode under the microscope. The manufacture of such electrodes, however, is difficult and time consuming. Furthermore, as a rule, the electrodes which are usable must be separated from a large number of defective electrodes produced. Moreover, the three dimensional manipulation of such electrodes under a microscope is very difficult, consequently; the simultaneous manual operation of several electrodes in order to probe various cells or parts of cells at the same time is not practically feasible. Such thin wire electrodes have an additional serious disadvantage in that they vibrate during manipulation, and this motion may cause the death of the cell being studied. Similar objections are applicable to the pipette electrodes, which are filled with an electrolyte, which are known in the art.